I've just gone through a folder of 20 photos, working through them in view mode (ie. full-size photo after double-clicking the thumbnail, but not full-screen), pressing Ctrl-I and filling in the Caption box before clicking Apply. I have the information panel on the screen configured to include {IPTC:Caption} and it appears shortly after clicking the Apply button, then I move onto the next photo. All well and good.

After finishing the 20 photos, I've gone back through them all, and the captions have all disappeared from all of them . No caption appears in the information panel, and going back into the Ctrl-I box, there's no caption in there either. I went back and re-captioned about 5 of them as before, the caption appeared in the panel before I moved on, but on going back to the photos again the captions had vanished again.

After a bit of cursing and swearing, I've found that if I add the captions from thumbnail mode, doing Ctrl-I as before on each one, they stay put - I've configured the thumbnail view to include the caption beneath each one, and they've all stayed on, and they all show on the photo when opened full-screen.